Good mental health at age 11 cuts the risk of being overweight or obese at 17, according to a study.

Researchers suggest age 11 “may be a sensitive period in which psychological wellbeing is associated with future body weight”.

The study by researchers at the University of Liverpool and Maynooth University, published in the journal Obesity, included more than 8,000 youngsters.

Data from 4,556 11-year-olds and 3,791 14-year-olds considered overweight or obese was analysed, with the group then followed up at age 17.

Psychological wellbeing was ranked using questions answered by children and their caregivers on issues such as self-esteem, happiness with life, depressive symptoms, social support, satisfaction with appearance and online bullying.

The study found better mental health and psychosocial wellbeing at 11 – but not 14 – was associated with the reversal of being overweight or obese by 17.

Among those classed as overweight or obese at age 11 or 14, about 16% – 12% of 11-year-olds and 4% of 14-year-olds – were considered a normal weight at 17.

Dr I Gusti Ngurah Edi Putra, from the Institute of Population Health at the University of Liverpool, said: “This study is the first to show how psychological wellbeing, specifically at age 11, plays an important role in explaining why some children transitioned into a healthy weight, but the others remained with overweight and obesity by age 17.

“While further work needs to be done to understand why early adolescence is a critical point, we know this is a time in a child’s life when they may be experiencing change – moving up into high school for example.

“Integrating psychological support into current obesity prevention and treatment, particularly during an age-sensitive period may be important.”

Professor Eric Robinson, also from the Institute of Population Health at the University of Liverpool, added: “We have known for some time that overweight and obesity are difficult to live with psychologically and these new findings align with other emerging evidence which suggest that as a society we need to be doing a much better job of supporting people with obesity if we are to ever make serious progress in reducing obesity.”